1. Field of the Invention
The field of art to which this invention relates is-printers, in particular, a curl-eliminator for a high volume printer having a top-feeder in which pre-printed stock is being feed into the printer for further printing.
2. Description of the Related Art
In printers of the prior art, particularly those which employ a top-feeder for storing and feeding paper into the printer, paper which is curled (i.e., has a smile) presents a problem in that it does not properly feed into the printer. Printing on paper that is pre-printed, such as forms or checks, is particularly troublesome because of the pre-printed paper's tendency to curl.
A typical printer 100 of the prior art having such a top-feeder paper feed arrangement is shown in FIG. 1. The top-feeder 102 generally includes a paper tray 103 and employs a pick roller 104 for contacting and feeding a sheet of paper 106 from the top of a paper stack 108 into the printer 100. A gearbox and motor assembly 110 drive the pinch roller as necessary to feed the paper 108. If the paper in the paper stack 108 is curled, as is shown in FIG. 1, the pick roller 104, which is generally located in the center of the paper along a central axis C--C, does not efficiently engage and feed the paper 108 into the printer 100.
Furthermore, since the paper 108 is curled upward, its ends 108a, 108b are elevated over its center 108c, resulting in at least one of the ends 108a striking unintended parts of the feeder, such as the gearbox and motor assembly 110. This causes the top sheet of paper 106 to rotate while feeding into the printer 100, resulting in improper feeding and a subsequent paper jam.
Devices are known in the prior art for the reduction and/or elimination of paper curl. While these devices have their advantages, they are generally complex and costly, such as that disclosed in U.S. Pat. No. 5,734,404 to Kumuro, et al. Their complexity and cost also make them difficult, if not impossible, to retrofit onto existing printers which do not have a curl elimination system. The prior art devices also do not account for a changing degree of paper curl, thus only reducing the curl in badly curled paper, not eliminating it.
For these reasons a curl eliminator is needed which is simple, inexpensive, easy to retrofit onto existing printers and accounts for the degree of paper curl in a stack of paper to be fed into a printer, particularly one which employs a top-feeder system.